Export-Paper-Model-from-Blender Add-on in 2.80?
It looks like the guy who makes the plug-in didn’t have time to update the code for the 2.8 beta.

His words: "It is, and will be in 2.80 release.
I just didn't finish the port, so these changes are not commited yet."

You can follow here: https://github.com/addam/Export-Paper-Model-from-Blender/issues/62